Chapter 609 Bell Palsy
Bell palsy is an acute unilateral facial nerve palsy that is not associated with other cranial neuropathies or brainstem dysfunction. It is a common disorder at all ages from infancy through adolescence and usually develops abruptly about 2 wk after a systemic viral infection. The preceding infection is caused by the herpes simplex virus, varicella-zoster virus, Epstein-Barr virus, Lyme disease, mumps virus, or Mycoplasma (Table 609-1). Active or reactivation of herpes simplex or varicella-zoster virus may be the most common cause of Bell palsy (Fig. 609-1). The disease is occasionally a postinfectious allergic or immune demyelinating facial neuritis. It also may be a focal toxic or inflammatory neuropathy and has been associated with ribavirin and interferon-α therapy for hepatitis C.
Table 609-1 ETIOLOGIES OF ACUTE PERIPHERAL FACIAL PALSY
COMMON
LESS COMMON INFECTIONS
OTHER LESS COMMON CONDITIONS
* Implicated in idiopathic Bell palsy.
† Noncaseating granulomas with facial (lips, eyelids) edema, recurrent alternating facial paralysis, family history, migraines, or headaches.
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